Attemperator for rotary kilns and the like



Jan. 2, 1934. J. s. FASTING ATTEMPERATOR FOR ROTARY KILNS AND THE LIKE Filed Feb. 11, 1932 A TTORNEYS.

J. 5. FASTING I 1,942,140

ATTEMPERATOR FOR ROTARY KILNS AND THE LIKE Jan. 2, 1934.-

Patented Jan. 2, 1934 PATENT OFFICE THE Johan S. Fasting,

Valby,

LIKE

near Copenhagen,

Denmark, assignor to F. L. Smidth & 00., New York, N. Y., a corporation of New Jersey Application February 11, 1932, Serial No. 592,427,

and in France April 11, 1931 2 Claims.

This invention has been developed and will be described with particular reference to the interchange of heat in rotary kilns as between the material being treated, such as cement raw materials, passing in one direction through the kiln, and a gaseous medium, such as hot air or the hot combustion gases from the lower part of the kiln, but it will be understood that the invention is capable of application to other industrial processes, in which an interchange of heat between the material treated and an aeriform fluid or gaseous medium is to be eiiected.

Many eiiorts have been made, especially in the manufacture of cement in rotary kilns, to increase efiiciency through a more effective utilization of the hot gases of combustion, from the lower part of the kiln, in the preliminary drying and in the calcination of the cement materials in the upper part of the kiln. Much has been accomplished, in comparison with the practices of the past, but it is well known that much of the heat of the combustion gases is lost by reason of imperfect transmission of the heat from the combustion gases to the material being treated and it is the object of the present invention to enable the heat of such gases to be transmitted in greater degree than heretofore to such material. It has been proposed heretofore to increase the contact of the material being treated with the aeriform or gaseous medium by forming the lining of the kiln in such manner that in the rotation of the kiln some of the material will be raised from the body of the material in the lower segment of the kiln and permitted to fall through the gaseous medium above such main body. Not only is the relative volume of material so exposed to the gaseous medium small, but the refractory substance of the lining is not of such a character as to absorb heat in large measure from the gaseous medium in the upper segment of the kiln or to yield its heat readily to the material in the lower segment of the kiln. It has also been proposed to place in the upper portion of the kiln, that is, toward the feeding end, metallic bodies, such as chains, 'which are heated in their passage through the body of gaseous medium and give up their heat to the body of material in the lower segment of the kiln and, in the wet process of cement making, lift the material into the body of gaseous medium. Metallic bodies, such as those heretofore employed, are unable to endure for any considerable period of time the very high temperatures (1400 to 1500 C.) of the gaseous medium and must be replaced at intervals. In the development of the present invention greatly increased efiiciency in attemperation can be secured through the use of a heat resistant steel for the heat transmitting bodies and by the shaping and positioning of such bodies so that they will absorb heat readily from the body of gaseous medium above the material being treated and will give up readily to such material, as they pass through it in the rotation of the kiln, the heat which they have absorbed from the gaseous medium. The heat transmitting members are secured to the shell of the kiln about its inner periphery, are projected somewhat toward the axis of the kiln, are so formed as to permit the passage of the gaseous medium and of the material in an axial direction, are thin so that their temperature will be quickly and materially reduced as they pass through the material in the lower segment of the kiln, and are so shaped that as they pass through such material they will stir it up somewhat, but without causing the material to be cascaded through the medium with the consequent and highly objectionable carrying on and ultimate discharge from the stack of the finer particles in the form of dust. Provision is also made for the attachment of the members to the kiln in such manner that the refractory lining of the kiln shall not be weakened or subjected to breaking stresses through the Xpansion or contraction of the metallic members. The invention will be more fully explained hereinafter with reference to the accompanying drawings in which it is illustrated, and in which:

Figure 1 is a view in longitudinal section of a portion of a kiln which embodies the invention.

Figure 2 is a view of the same in transverse sectional elevation.

Figures 3 and l are views similar respectively to Figures 1 and 2, but showing a slightly different embodiment of the invention.

The kiln has a metal shell which, as usual, is provided with a refractory lining 2, which may be formed in any usual or suitable manner. In the construction shown in Figures 1 and 2 attemperating or heat transmitting members 3 are shown as sectional rings which are secured to the kiln in such manner that the refractory lining of the kiln is not weakened or subjected to breaking stresses through the expansion or contraction of the metallic members. To this end each of such members is formed of an annular series of independent sections 3 each section being formed with a foot 3 which bears against and is secured to the shell 1 of the kiln as by a bolt 4 each section being also formed with extensions 3 which bear upon the lining, being preferably set into the same slightly, as clearly lib shown in Figure 2, but without penetrating the lining deeply. These members, being secured to the inner periphery of the shell, are projected inwardly therefrom toward the axis of the kiln and they are also shown as notched at intervals, nearly or quite to the lining, as at 3 so that they do not interfere materially with the passage either of the material or of the aeriform or gaseous medium longitudinally through the kiln, They are shown as disposed substantially transverse or at right angles to the axis of the kiln but obviously they might be inclined or otherwise disposed or formed so as to promote or retard the passage of the material as may be desired.

It will be observed that the heat transmitting members have no lifting action on the material and that the material therefore is not permitted to fall or to be cascaded through the gaseous medium with the consequent release of the finer particles in, the form of dust to be carried on with the hot gases through the kiln and into the stack from which the dust would be spread upon the surrounding country to its detriment besides loss of material.

In the embodiment of the invention shown in Figures 3 and 4 the shell 1 is provided with a refractory lining 2 and the attemperators or heat transmitting bodies 3 being formed, as in the construction shown in Figures 1 and 2, of an annular series of independent sections 3, each with a foot 3 to bear against the shell and with extensions 3! tobear against the refractory lining, substantially as described with respect to Figures 1 and 2, are secured to the inner periphery ofv the mill, project inward toward. the axis, being cut away so as to offer little obstruction to the passage of the material or gaseous medium and are provided each at its inner end with a flange or fin 5 which is extended generally in an axial direction and at a small angle to theshell,

serving also to effect a stirring of the material during the rotation of the kiln, but without causing it to be lifted and cascaded through the gaseous medium with the objectionable release of dust.

It will be understood that the arrangement and form of the heat transmitting bodies or attemperators may be modified to suit different conditions of use.

- I claim as my invention: 1. The combination with a rotary shell provided with a refractory lining and adapted to be traversed by material to be treated and by a gaseous medium and relatively thin, metallic members substantially transverse to the axis of the shell projected inwardly from the inner periphery of the shell to pass through the material and the gaseous medium in alternation and formed to permit the passage of the material and the gaseous medium in an axial direction, each such member being formed-of an annular series of independent sections, each section being formed with a footbearing against and secured to the shell and with extensions to bear upon the lining without penetrating the same deeply.

2. The combination with a rotary shell provided with a refractory lining and adapted to be traversed by material tobe treated and by a gaseous medium and relatively thin attemperators of heat resistant steel substantially transverse to the axis of the shell projected inwardly from the inner periphery of the shell to pass through the material and the gaseous medium in alternation and formed to permit the passage of the material and the gaseous medium in an-axial direction, each such attemperator being formed as an independent section provided with a foot bearing. against the shell and with extensions to bearupon the-lining without penetrating the same deeply and having a fin at a small angle with respect to the shell and extended in an axial direction.

JOHAN S. FASTING. 

